> I think we reached peak multiscreen ~2010 and it's sort of falling out of favour these days
When we upgraded monitors at work I took several of the old ones to see how many monitors I could connect. I got up to 5 I believe (with one being a new ultrawide). It was impossible to use them all productively. At best they could serve as live status for some Jenkins job. Two monitors are useful, but now you can just use one ultrawide (I like to use two cables since it makes Window management easier, but you can use software for that too). I like to have one extra in addition to an ultrawide, but it's often unused.
I use tripe 4K monitors all the time and it's a very productive setup. Left is video conference, far enough away that I can use it without glasses if I want to, front is development work, browser, email, right is the live view of the application that I'm working on. And at $500 each the price really isn't an obstacle if you are using them professionally.
I use Spectacle for window management on a 49" ultrawide and it works great for dividing the screen into 3 segments. Having one window centered helps avoiding too much horizontal movement of my neck as well (which I've been recommended to avoid by a physiotherapist).
Most environments snap windows to borders of logical screens.
If the OS believes the ultrawide is actually two 4:3 monitors, you'll get one such snapping range right in the middle.
If you connect the monitor with one cable, the OS believes it's one single 21:9, but if you connect them with two cables, the OS believes it's two smaller monitors.
Windows also works this way, IDK about linux.
FWIW Samsung's ultra wide monitors are supposed to support splitting the screen up into multiple areas for the purpose of window management, even when using a single cable.
When we upgraded monitors at work I took several of the old ones to see how many monitors I could connect. I got up to 5 I believe (with one being a new ultrawide). It was impossible to use them all productively. At best they could serve as live status for some Jenkins job. Two monitors are useful, but now you can just use one ultrawide (I like to use two cables since it makes Window management easier, but you can use software for that too). I like to have one extra in addition to an ultrawide, but it's often unused.